What test can be done with a DVM to determine if the bias port in the output section of an amp is where it suposed to be?
Sometimes i get amplifers other tech has tried to repair an maybe change the bias settings.so i just want to no how to go about finding where it suposed to be.
If the manufacturer has specific settings, use those. For generic amps where there is no information available for bias settings, I use the amp meter on the 12v power supply.
Set the bias at the full minimum. Rotate the pot slowly until the amp meter just barely begins to move. That indicates that the outputs are biased slightly on. If you're not familiar with the amp, you should runt it up to near thermal to confirm that the bias/idle current doesn't increase significantly at high temperatures. The following demo shows the basic procedure.
http://www.bcae1.com/temp/ausettingbias.swf
Set the bias at the full minimum. Rotate the pot slowly until the amp meter just barely begins to move. That indicates that the outputs are biased slightly on. If you're not familiar with the amp, you should runt it up to near thermal to confirm that the bias/idle current doesn't increase significantly at high temperatures. The following demo shows the basic procedure.
http://www.bcae1.com/temp/ausettingbias.swf
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